Photographic material containing 2 4 dithioxo-1 2 3 4 tetrahydro-1 3 5 triazines

ABSTRACT

THE USE OF 2,4 -DITHIOXI- 1,2,3,4-THTRAHYDRO-1,3,5-TRIAZINES, OR THE TAUTOMERIC FORMS THEREOF AS ANTI-BRONZING AGENTS IN PHOTOGRAPHIC MATERIALS AND PROCESS IS DESCRIBED.

United States Patent 01 ice 3,625,690 Patented Dec. 7, 1971 US. C]. 96-52 11 Claims ABSTRACT OF THE DISCLOSURE The use of 2,4 dithioxo l,2,3,4-tetr-ahydro-1,3,5-triazines, or the tautomeric forms thereof as anti-bronzing agents in photographic materials and processes is described.

The present invention relates to compounds, which prevent the images obtained in photographic printing materials from being bronzed on hot glazing or mechanical drying at elevated temperature, and to the use of said compounds in light-sensitive photographic materials and in photographic processing baths.

The images obtained in light-sensitive silver halide emulsion layers of a photographic printing material often undergo changes during hot glazing or mechanical drying at elevated temperature since during these treatments a loss of density arises which is also called plumming or bronzing of the silver image.

It is known to incorporate small amounts of chemical compounds into light-sensitive material containing a silver halide emulsion printing layer, or into processing baths for such material in order to prevent this loss of density.

It has now been found that when incorporating into a light-sensitive material having at least one silver halide emulsion layer or when dissolving in at least one of the processing baths for such material at least one 2,4- dithioxo-1,2,3,4-tetrahydro-1,3,5-triazine corresponding to the following general formula wherein R stands for alkyl including substituted alkyl, cycloalkyl including substituted cycloalkyl, aralkyl including substituted aralkyl or aryl including substituted aryl or a tautomeric form thereof or a salt of such tautomeric form practically no loss of density of the developed silver containing image occurs on hot glazing or drying at elevated temperature.

When the anti-bronzing agents according to the above general formula are incorporated into a light-sensitive material they may be present in a light-sensitive silver halide emulsion layer and/or in at least one water-permeable layer coated at the same side of the support as the said emulsion layer. Moreover, the said antibronzing agents must not necessarily be present in the light-sensitive material for exerting their antibronzing action but may also be present in at least one of the baths for processing the photographic material.

Representative examples of compounds corresponding to the above general formula are:

1-phenyl-2,4-dithioxo-1,2,3,4-tetrahydro-1,3,5-triazine 1-cyclohexyl-2,4-dithioxo-1,2,3,4-tetrahydro-1,3,5-triazine 1-benzyl-2,4-dithiox0- l,2,3,4-tetrahydro- 1,3,5 -triazine 1-p-tolyl-2,4-dithioxo-1,2,3,4-tetrahydro- 1,3,5 -triazine These compounds can be prepared by reaction of appropriate isonitriles with thiocyanic acid 'as described in Ann. Chem. 670 (1963), '80 by I. Ugi and F. K. Rosendahl.

When the antibronzing agents according to the above formula are incorporated into one of the component layers of the light-sensitive material, they do not only prevent the silver-containing image from losing density on hot glazing or drying at increased temperature as described before, but they also reduce the fog without influencing the sensitivity and gradation to any noteworthy extent. When incorporating the said anti-bronzing agents of use according to the invention into the photographic material, they are generally incorporated into the light-sensitive silver halide emulsion layer itself. They can be added to the silver halide emulsion at any moment during its preparation, but preferably after chemical ripening or just before coating. This addition occurs in general from a solution of the compound in an appropriate solvent such 'as water, alcohol, ethyelne glycol monomethyl ether, dimethylformamide, dioxan and so on. Instead of incorporating the compounds into the photographic layer, they can also be incorporated into an additional water-permeable layer such as a gelatin covering layer or an intermediate layer. Mixtures of different compounds according to the above general formula may be used as well.

The total concentration of antibronzing agent according to the present invention in the light-sensitive material may vary within wide limits, but is preferably chosen in such a way that per sq. m. of light-sensitive material from some mg. to approximately 500 mg. of compound or compounds are present.

Light-sensitive material according to the present invention may comprise any silver halide emulsion layer such as for instance a gelatino silver chloride emulsion layer, a

gelatino silver chlorobromide emulsion layer, a gelatino silver chloroiodide emulsion layer, a gelatino silver bromide emulsion layer, a gelatino silver bromo-iodide emulsion layer and a gelatino silver chlorobromo-iodide emulsion layer, The silver halide emulsion may. contain any known additives, such as anti-fogging agents, stabilizers, hardening agents, plasticizers and dispersing agents. Further, the emulsion may be sensitized chemically as well as spectrally. It may be chemically sensitized by effecting the ripening in the presence of small amounts of sulphur containing compounds, for instance allyl isothiocyanate, allyl thiourea, sodium thiosulphate and so on. The lightsensitive emulsions can also be sensitized by means of reducing agents for instance the tin compounds described in the Belgian patent specifications 493,464 and 568,687, the iminoaminomethane sulphinic acid compounds described in the British patent specification 789,823 or by means of small amounts of noble metal compounds such as gold compounds, platinum compounds, palladium compounds, iridium compounds, ruthenium compounds and rhodium compounds. Furthermore, it is also possible to sensitize the emulsions with polyoxyalkylenes, for instance polyoxyethylene of a molecular weight ranging between 1000 and 20,000 or condensation products of polyalkylene oxides with aliphatic alcohols, glycols, cyclic dehydration products of hexitols, alkyl-substituted phenols, aliphatic carboxylic acids, aliphatic amines, aliphatic diamines and aliphatic amides. The condensation products have a molecular weight of at least 700, preferably of more than 1000. For attaining special effects these sensitizers, of course, can be applied in combination as described in Belgian patent specification 537,278 and in British patent specification 727,982.

Instead of incorporating the compounds to be used according to the invention into the photographic material, prior to coating, they can be dissolved in any processing bath such as the developing bath, the fixing bath, an additional hardening bath, and a bath which contains surface-active compounds and which may be used as a last treating bath before hot glazing or before drying at elevated temperature the image-containing material. When the photographic material is led through such a bath, it absorbs a certain amount of the said antibronzing agent into its Water-permeable layers, which assures the retaining of the density of the silver-containing image during hot glazing or drying at a high temperature as successfully as in the case when the antibronzing agent is present in the light-sensitive material from its preparation on. For incorporating the antibronzing agent according to the invention into the photographic material said material can be treated prior to hot glazing or drying at elevated temperature with a bath containing a mere solution of said antibronzing agents. When the antibronzing agents according to the above general formula are dissolved in one of the above baths, they are mostly dissolved in the form of their alkali metal salts in concentrations which can vary within very wide limits preferably, however, between approximately 50 mg. and approximately 3 g./liter.

The following examples illustrate the invention.

EXAMPLE 1 Material 1 Material 1 is prepared as follows:

A gelatino silver chloride emulsion prepared with a proportion of silver nitrate to gelatin of 1 to 4 (28.3 g./ 113.2 g. per kg. of emulsion) is applied to a barytacoated paper support in such a way that after drying an amount of silver halide, equivalent to 1.5 g. of silver nitrate is present per sq. m. of light-sensitive material. This light-sensitive layer is overcoated with a thin gelatin covering layer which is hardened afterwards.

Material 2::

Material 2a is prepared as material 1 with the ditference, however, that per kg. of light-sensitive emulsion, ready for coating, 1 g. of 1-cyclo'hexyl-2,4-dithioxo- 1,2,3,4-tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

Material 2b Material 2b is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion, 'ready for coating, 1 g. of 1-cyclohexyl-2,4-dithioxol,2,3,4-tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

Material 3a Material 3a is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion ready for coating, 0.3 g. of 1-p-tolyl-2,4-dithioxo-1,2,3,4- tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

Material 3b Material 31) is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion, ready for coating, 1 g. 1-p-tolyl-2,4-dithioxo-1,2,3,4- tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

A strip of each of these 5 materials is exposed for some minutes and developed for five minutes at 20 C. in a bath of the following composition:

water-800 ccs.

p-monomethyl aminophenol sulphatel.5 g. anhydrous sodium sulphite-SO g. hydroquinone6 g.

anhydrous sodium carb0nate32 g. potassium bromide-2 g.

water up to 1000 ccs.

The 5 material strips are rinsed for a moment and then fixed for five minutes at room temperature in the following composition:

water-800 ccs.

anhydrous sodium thiosulphate-120 g. potassium metabisulphite25 g.

water up to 1000 ccs.

The five material strips are finally pressed for 6 minutes with their image-containing side against a polished plate at C.

The density of the various material strips is measured with a Macbeth densitometer before as well as after hot glazing. The following results are attained:

Maximum density BE re hot After hot glazing glazing Material 1 (comparison material) 2. 02 1. 60 Material 2a 2. 10 2. 02 Materi 2b.. 1. 96 2. 16 Material 3a- 1. 94 1. 80 Material 36.... 1. 96 2. 04

EXAMPLE 2 Material 1 Material 2a Material 2a is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion, ready for coating, 0.3 g. of 1-cyclohexyl-2,4-dithioxol,2,3,4-tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

Material 2b Material 2b is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion, ready for coating, 1 g. of 1-cyclohexyl-2,4-dithioxo- 1,2,3,4-tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

Material 3a Material 3a is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion,

ready for coating, 0.3 g. of 1-p-tolyl-2,4-dithioxo-1,2,3,4- tetrahydro-l,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

Material 3b Maximum density Before hot After hot glazing glazing Material 1 (comparison material 1. 84 1.31 Material 2a 1. 82 1. 74 Material 21). 1. 78 1. 80 Material 3a 1.90 1. 78 Material 3b 1. 82 1. 80

EXAMPLE 3 Material 1 Material 2a Material 2a is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion, ready for coating, 0.3 g. of 1-cyclohexyl-2,4-dithioxo- 1,2,3,4-tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

Material 217 Material 2b is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion, ready for coating, 1 g. of 1-cyclohexyl-2,4-dithioxo- 1,2,3,4-tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

Material 3a Material 3a is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion, ready for coating, 0.3 g. of 1-p-tolyl-2,4-dithioxo-1,2,3,4- tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

Material 3b Material 3b is prepared as material 1 with the difference, however, that per kg. of light-sensitive emulsion, ready for coating, 1 g. of 1-p-tolyl-2,4-dithioxo-1,2,3,4- tetrahydro-1,3,5-triazine is added from a 1% solution in ethylene glycol monomethyl ether.

A strip of each of these materials is treated in a similar way as the material strips of Example 1 and the following results are attained.

Density Before hot After hot glazing glazing Material 1 (comparison material) 1. 76 1.30 Material 2a 1. 86 1. 80 Material 2b 1. 82 1.72 Material 3a 1.86 1. 74 Material 3!) 1. 71 1. 63

We claim:

1. Process for hot-glazing or mechanically drying at elevated temperature an image-wise exposed developed and fixed photographic material comprising at least one silver halide emulsion layer, wherein said photographic material when being hot glazed or mechanically dried is in working contact with a 2,4 dithioxo-1,2,3,4 tetrahydro- 1,3,5-triazine corresponding to the formula:

r RN\ /NH C II 8 wherein: R stands for an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group.

2. The process of claim 1 wherein said triazine is present in its tautomeric form.

3. The process of claim 2 wherein said tautomeric triazine is present in salt form.

4. Photographic material comprising at least one lightsensitive silver halide emulsion layer wherein said lightsensitive silver halide emulsion layer is in working contact with at least one 2,4 dithioxo-1,2,3,4 tetrahydro-1,3,5- triazine corresponding to the formula:

wherein: R stands for alkyl group, a cycloalkyl group, an aralkyl group or an aryl group.

5. The photographic material of claim 4 wherein said triazine is present in its tautomeric form.

6. The photographic material of claim 5 wherein the tautomeric triazine is present in salt form.

7. The photographic material of claim 4 wherein the triazine is contained in said light-sensitive silver halide emulsion layer.

8. The photographic material of claim 4 which includes a support and said triazine is contained in a water-permeable layer present at the same side of said support as said light-sensitive emulsion layer.

9. Photographic processing bath containing an active processing ingredient and at least one 2,4 dithioxo1,2,3,4 tetrahydr0-1,3,5-triazine corresponding to the formula:

wherein: R stands for an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group.

10. The photographic processing bath of claim 9 wherein said triazine is present in its tautomeric form.

11. The processing bath of claim 10 wherein said tautomeric triazine is present in its salt form.

References Cited UNITED STATES PATENTS 2,668,113 2/ 1954 Schwalenstocker 9652 3,017,270 1/1962 Tregillus et al 9629 3,335,009 8/1967 Rasch et a1. 96-61 NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner US. Cl. X.R.

96-5.0, 61 X, 66, 67 UX, UX 

